BILLINGS — Montana Fish, Wildlife and Parks – in a cooperative effort with Wyoming and federal biologists – will treat 28 miles of streams northeast of and within Yellowstone National Park next week to remove non-native brook trout and enhance the viability of native Yellowstone cutthroat trout.
The project is a cooperative effort involving FWP, Wyoming Game and Fish Department, Custer Gallatin National Forest, Shoshone National Forest and Yellowstone National Park. It involves treating streams and tributaries in the Soda Butte Creek drainage, from its headwaters in the Beartooth Mountains downstream to Icebox Canyon, approximately 10 miles from its confluence with the Lamar River in northeastern Yellowstone National Park.
Starting later this week, biologists and technicians will use electrofishing equipment to collect as many native Yellowstone cutthroat trout as possible from the drainage and temporarily move them to nearby tributaries. Starting Aug. 24 the biologists will treat all streams in the drainage with rotenone, a piscicide intended to remove all remaining fish. Biologists are targeting non-native brook trout.
When treatment is complete – anticipated by Sept. 1 – biologists will return the rescued Yellowstone cutthroat trout to the drainage.
Soda Butte Creek supports a slightly hybridized population of cutthroat trout and non-native brook trout. Brook trout are an invasive species that can eliminate native cutthroat trout within a few decades following invasion. Brook trout originated from fish stocked in Montana. However, they are invading downstream into Yellowstone National Park. This project is intended to eradicate brook trout and prevent them from spreading into the greater Lamar River watershed.
The watershed that encompasses Soda Butte Creek and the Lamar River is among the nation’s largest connected stream systems supporting Yellowstone cutthroat trout. It was scheduled for treatment because of potential consequences from the threat posed by invasive brook trout.
Plans developed by state and federal agencies provide the foundation for Yellowstone cutthroat trout conservation. In Montana, the need for this project comes from a commitment by state and federal agencies to ensure a long-term, self-sustaining population while maintaining genetic diversity and integrity and protecting the ecological, recreational and economic values associated with Yellowstone cutthroat trout.
For more than a decade, state and federal partners have tried to remove fish from the watershed using electrofishing. The effort has been prohibitively expensive and ineffective at eradicating brook trout. Continued pursuit of that alternative is infeasible.
Piscicides such as rotenone are effective at removing all fish. Angling is inefficient and cannot target young-of-the-year fish. Many of the tributaries are steep, small streams covered with deadfall timber, making angler access unlikely. And any reduction in brook trout numbers (without eradicating the species) would free up food, shelter and space resources for the next generation of brook trout.
Rotenone is a naturally occurring chemical compound derived from the roots of certain tropical plants. It acts by interrupting part of the fish’s breathing process. It is effective on fish because it is readily absorbed into the bloodstream through the thin cell layer in gills. It is either dripped or sprayed into streams or springs at very low concentrations.
Rotenone naturally attenuates quickly with sunlight and is rapidly absorbed by organic substances in the water. Biologists will add potassium permanganate to water at the lower bounds of the treatment area to fully detoxify rotenone and prevent impacts to downstream waters.
Rotenone in extremely high concentrations could have some effects on animals other than fish. However, in the concentrations used on Soda Butte Creek, only those animals that breathe with gills will feel any effect.